1. Technical Field
The present invention relates to an image display apparatus, a projector, a control method and an information storage device.
2. Related Art
When an audio output device outputs a mixture of a microphone sound signal and a non-microphone sound signal, if the non-microphone sound (e.g., BGM) is louder than the microphone sound, the microphone sound becomes hard to be heard. Further, when the microphone sound signal is newly input while the non-microphone sound is output, excess of allowable output range of a speaker occurs, which might cause the sound to quaver (might cause so called a chattering noise). In an image display apparatus equipped with a low-price audio output device, such a problem to solve occurs notably.
As a measure for solving such a problem, there is described in, for example, JP-A-5-64286 a microphone mixer circuit provided with a switch, which is turned on upon insertion of a microphone plug into a microphone input socket, and a circuit, which lowers the music level input to the mixer when the switch is turned on.
However, according to the measure of JP-A-5-64286, since the music level drops upon insertion of the microphone plug to vary the output sound even in the case in which no microphone sound signal is input, the audience feels uncomfortable. Further, according to the measure described above, since the music level is lowered along a fixed pattern irrespective of the circumstances, it is not possible to perform an optimum audio output corresponding to the circumstances.